JPH05508819A - polyhydroxy acid film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] polyhydroxy acid film Background of the invention The present invention provides certain polyhydroxy acid compositions and products made from these compositions. , relates to films useful as degradable packaging materials.

High molecular weight polymers of hydroxy acids, and alpha hydroxy acids especially glycols. The cyclic dimer products from esterification of lactic and lactic acids can be degradable. Conditions that are well known and exist in the natural environment or used in suitable waste treatment facilities. Disposable materials that substantially and readily degrade to harmless by-products under the conditions in which they are used. It has been found useful in packaging.

Packaging materials have optical clarity, tensile strength, scratch resistance and optional shrinkage. It is desirable for the material to have additional beneficial physical properties, including physical properties. contraction Polymer films are useful in "shrink wrap" packaging. shrink wrapping to it Therefore, a film structure placed around a material can add convective or radiant heat. and shrink to provide a tight, protective, self-sealing container. It's a method. To make the polyhydroxy acid film shrinkable, the polyhydroxy acid film must be The silicic acid film must be oriented by a mechanical stretching process.

Many commercially important high molecular weight polyhydroxy acids have large proportions of inherent chirality. It contains carbon atoms and therefore can be quite crystalline and brittle. Such a polymer - Can withstand harsh film forming and orientation processes without excessive film destruction It is poorly tolerated and results in low yields. Furthermore, considerable crystallinity The polyhydroxy acid film may become brittle with aging.

One way to make flexible polyhydroxy acid films is to use large amounts of monomer or By incorporating low molecular weight oligomeric alpha polyhydroxy oxidation species , to plasticize the film. However, such plasticized polyhydride Roxy acid compositions can stick to film forming equipment and produce films of non-uniform thickness. Difficult to extrude into film as the plasticizer often contaminates equipment. It is. Even when successfully processed into film form, plasticized polyhydrocarbons The oxyacid composition itself has a glass transition temperature Tg close to ambient temperature, and has a warm temperature. It is not stable under storage conditions found in harsh climates. In addition, plasticized polyhydro The oxy-acid composition is used to maintain structural integrity for the intended useful life of the package. However, if the film is still shrinkable, heat required for good adhesion to the product and good package strength when Unable to show set contraction force.

Schneider, U.S. Patent No. 2.703,316 In issue, the production of film from lactic acid is disclosed. Schneider's commercially available Polylactic acid from lactic acid is inherently racemic (optically inactive) and therefore The films produced therefrom are highly plasticized polyhydroxy acid compositions. It may have the same drawbacks as that of . Commercially useful, single-use packaging applications include: Economically and with high yield, optically clear, durable, and biaxially oriented films can be produced. It is desirable to provide degradable compositions that can be processed.

Summary of the invention According to the present invention, the production of a degradable and shrinkable polymer film consists of the following steps: A manufacturing method is provided.

(a) Melt-process the polymer material while sufficiently mechanically stirring the melt, and Obtain a homogeneous composition containing the following components: (1) at least one selected from the following: 92 to 99.9% by weight polyhydroxy acid containing a hydroxy acid component of polymer: (i) (QC mouth "C00CR'R" Co).

(100) [0(CR’R”)Co]p (Mountain) (OCR’R″CR’R″OCR’also”Co).

(iv) (OCR’ R” CR’ R” OCR’ R” CR’ R” Co).

(v) a copolymer of (i)-(iv) and a non-hydroxy acid comonomer, where n is 2.4 or 5: psqsr and S are integers, and their sum is approximately The range is from 350 to 5,000, R1 and RI + are hydrogen, and 1 to 5,000. Hydrocarbyl containing 12 carbon atoms or substituted containing 1 to 12 carbon atoms is a hydrocarbyl with sufficient molecular weight to produce a self-supporting film. have, (II) Monomeric hydroxy acid, cyclic dimer of monomeric hydroxy acid, acyclic dimers of monomeric hydroxy acids and monomers with molecular weights up to 450. 0.10 to 8% by weight of plasticizers, including other oligomers of droxy acids; ( b) Forming the composition into a film of uniform thickness from about 0.05 to 2 mm. ; (C) The film thus produced is adjusted to the glass transition temperature of the polyhydroxy acid. The film is processed at a temperature higher than 200°C and lower than the melting point of the composition. Biaxially oriented Ru.

Also, a degradable, non-shrinkable polymer fibre, with a shrinkage value of less than 5% at 100°C. A method of manufacturing a lum is also provided.

Additionally provided are articles made by the method described above.

Detailed description of the invention The degradability of the films produced by the present invention is reduced by the use of polyhydroxy acids. achieved. As used herein, "polyhydroxy acid" refers to a polymer containing at least one hydroxy acid moiety selected from say: (’) (OCR’ R” C00CR’ R” CO) q(i i) [ 0(CR’R”)CO]p (i i i) (OCR’ R” CR’ R” OCR’ R” Co) .

l v) (OCR’ R” CR’ R” OCR’ R” CR’ R” CO) 5(v)(i)-(iv) copolymer with non-hydroxy acid comonomer where n is 2.4 or 5: psqSr and S are integers; The sum of is in the range of about 350 to 5,000, and R1 and Rr are hydrogen, hydrocarbyl containing 1 to 12 carbon atoms; or hydrocarbyl containing 1 to 12 carbon atoms; It is a substituted hydrocarbyl.

Examples of suitable non-hydroxy acid comonomers are lactide or lactic acid (e.g. Ron-caprolactone, beta-propiolactone, alpha, alpha-zime Lactones such as chill-beta propiolactone and dodecanolactone; condensation with other hydroxy acids such as glycolic acid; and amino acids) Including those that can be polymerized. For a more complete listing, see U.S. Patent No. 4,800, See No. 219, column 9, line 27. The values of p, q, r and S are selected to provide a suitable degree of crystallinity and rate of crystallization for the production of lume.

Polyhydroxy acids can be produced by polymerization directly from hydroxy acid precursors or by polymerization. By polymerization of lactones of cyclic monomers or cyclic dimers of droxy acid precursors be synthesized. Where polyhydroxy acids are produced from one or more lactones In this case, the selection of the cyclic monomer or cyclic dimer species as the polymerization monomer will depend on the type of hydroxy acid. Polymerization from cyclic lactones is Equilibrium reactions with intermediates, cyclic dimers, and low molecular weight species occur from hydroxy acids. High molecular weight polymers provide a practical limit to the molecular weight of directly produced polymers. Preferred for the production of hydroxy acids.

The polyhydroxy acids of the present invention form supportable films from polymer melts. have a molecular weight at least high enough to obtain sufficient viscosity and strength for . Average molecular weight ranging from about 50,000 to about 600,000; preferably about Polyhydroxy having an average molecular weight from 150,000 to about 450,000 Acids are useful in this invention. If the molecular weight is too high, it will be difficult to melt process the composition. Excessive deterioration occurs at temperatures that occur.

As used herein with respect to polyhydroxy acids, the term "degradable" The polyhydroxy acid moiety of the degradable material is biodegradable and more importantly means that it is degradable by hydrolysis. The rate of deterioration is determined by its intended use. (for example, a product does not deteriorate appreciably with normal storage and use, but if it is discarded) after which it deteriorates in a reasonable amount of time). For hydrolytic degradation, slightly acidic Neutral or basic conditions are advantageously used. The rate of hydrolytic degradation depends on the polymer bond. Affected by crystallinity and amount of water exposed. As a result of hydrolytic deterioration, The monomer units may be recovered if reconversion to a useful polyhydroxy acid is desired. Alternatively, the monomer units may be disposed of as environmentally friendly waste.

"Cloudy" products are generally outside the scope of this invention and include films of low molecular weight plasticizers. caused by extrusion to the surface or high crystalline content of the starting polymer It has poor transparency.

The term "ambient temperature" refers to the temperature to which the film product is exposed during use or storage. The highest temperature that will occur. This is usually at room temperature (28°C) or below refrigeration. range from below 40°C to 40°C or above in warehouse storage.

The preferred polyhydroxy acid of the present invention has 55-99 mol% of which Rr is hydrogen. , RI+ is a methyl group, and 80-97 mol% of the asymmetric carbons are in the R-configuration. and 3-20 mol% S-configuration, or 80- 97 mol% S-configuration and 3-20 mol% R-configuration. The main component consisting of the hydroxy acid component of (i) mentioned above, which is 1-45 mol% of the total R- or is an asymmetric carbon in which the S-configuration does not exceed 97 mol% of the asymmetric carbon. the hydroxy acid moiety of (i) having an elemental content, or (i) of (1v) a small amount of any hydroxy acid or a suitable non-hydroxy acid comonomer It is an ingredient.

Preferred polyhydroxy acids include, for example, 90 mol% of the asymmetric carbon atoms in the S-configuration. The main component consists of 65 mol% hydroxy acid component (1) May contain.

In this example, the minor component is 35 mole %, entirely the hydroxy acid component. (11) or a suitable non-hydroxy acid comonomer. This same In the same example, the minor component may be an additional hydroxy acid component (i). However, in the minor components, the fraction of asymmetric carbon in S-configuration is mainly Increases the total S-atom content to 97 mol% or more when added to the S-atoms of essential components. It must not be greater than a fraction that does not exist.

In a more preferred embodiment of the present invention, R- or The range of S- and S-asymmetric carbon atoms is 85-96 mol%, with major and minor components. The total R- and S-asymmetric carbon atoms in the portion do not exceed 96 mol%.

The terms "R-" and "S-" refer to stereoisomeric configurations of asymmetric carbon atoms. standard nomenclature for identifying applications. R- and S shown here - The percentage of carbon in the polymer chain, not the total carbon atoms in the polymer chain. refers only to the fraction of asymmetric carbon. An asymmetric carbon atom has different substituents attached to it. It has as many as four.

Polymers containing more equal fractions of R- and S-carbon atoms are 1) 2) have adjacent layers that often adhere to each other; Preferred compositions are selected to produce films that are susceptible to degradation during film processing. has a narrow range of asymmetric carbon atoms selected.

Also, films outside these ranges are cloudy and/or brittle. for example, Polymer films with a fraction in excess of 97% S-carbon atoms are Substantially crystalline after heat treatment as in manufacture. Crystallization is in film form performance, optical clarity of films formed from crystalline polymers, and For the production of well-oriented films formed by stretching from reamers. Harmful. Crystalline polymer films are also better than amorphous polymer films. It's also fragile. Reduce the negative effects of highly crystalline polymers on film properties The method involves incorporating chemical species of monomers and low molecular weight oligomers into a polymer matrix. plasticizing the polymer by incorporating and dispersing it. The port of the present invention Plasticizers for monomeric hydroxy acids, monomeric hydroxy acids, Lactide of hydroxy acids, lactyl lactyl acyclic dimer of monomeric hydroxy acids and and other oligomers of heptameric hydroxy acids with molecular weights up to 450. Ru.

Excessive concentration of plasticizer in polyhydroxy acids will result in films of non-uniform thickness. It is known that When the film is made by casting it onto a drum Excess plasticizer will separate from the film and stick to the drum, staining it. , or the film may be stuck to the drum.

For this reason, it is necessary to use polymers containing minimal amounts of plasticizers. know. of plasticizers necessary to obtain films useful in accordance with the present invention. The amount is from about 0.10 to about 8% by weight, preferably from about 0.2 to 6% by weight. be. A highly preferred composition range is about 0.2 to 0.4% by weight plasticizer. Ru. These plasticizer levels depend on the potency in the raw materials used to make the film. based on the concentration of hydroxyacid and plasticizer, and not necessarily the composition of the present invention. does not correspond to the concentration of plasticizer in the film produced.

Plasticizer content is determined by Applied Polymer Science, Cohn, Pan den Barbe, Pan de Ri Dar and Feyen, Vol. 29, pp. 4265-4277 (1984) [Jo Urnal of Applied Polymer 5science, Kah n, Van den Betg, Van de Ridder and Fe 7en, volume 29. pages 4265-4277 (1984) It can be determined by the lactide content analysis method taught in Ko. plasticizer If it becomes necessary to reduce the concentration of plasticizer in the latch composition, a separation step may be used. or during film extrusion. extrudcr) may also be used.

Shrinkage value is an indicator of film shrinkage performance. The shrinkage value is 1) from the oriented film, 10cm Cut out a 10 cm square sample; 2) Soak the sample in boiling water for 1 minute; 3) Measure and average the length and width of the boiled film; 4) Measure the length and width of the boiled film; Percentage is calculated by subtracting the average length and width from 10, then multiplying the difference by 10. Calculate the shrinkage value; depending on the case. For example, the flattening of a boiled film sample Assuming that the average length and width are 6 cm, the shrinkage value of the film is (10-6). 10, or 40%.

The polymer compositions of the present invention may have a diameter ranging from about 0.05 to 2 mm prior to orientation. Formed into a film of uniform thickness.

Film formation is from melt extrusion and sheet casting, blow molding, solvent by precipitation or other means well known for producing films from polymers. can be achieved. The film thus formed is directly fed to an orientation device. may be supplied, wound on spools for storage, or otherwise used (collected). It may then be processed or used.

Polymer films useful for shrink wrap applications include the polyhydroxy acid compositions discussed previously. It can be prepared by two-wheel orientation of a composite film. Biaxial orientation makes the film the direction in which it moves (called the machine direction (MD)), and in the plane of the film. along a direction 90 degrees to the machine direction (known as the transverse direction (TD)) Stretch the film, thereby reducing the initial MD and TD force dimensions of the film. This means extending it to at least twice as long. The biaxial orientation of the present invention is characterized by simultaneous MD and TD stretching, and continuous stretching. One method of simultaneous biaxial orientation is to Blowing a tube-shaped film while stretching the tube in the machine direction . Biaxial orientation increases the film temperature above and below the glass transition temperature of the polyhydroxy acid. This is done while heating and maintaining the temperature below the melting point. Glass transition temperature of polyhydroxy acids is measured by differential scanning calorimetry (DSC). The glass transition temperature is decreases with increasing amount of plasticizer, for compositions containing 0.28% by weight of plasticizer. for compositions containing 20% by weight plasticizer, but at 40°C. Only. High plasticizer concentrations result in lower glass transition temperatures in warmer climates. Undesirable as it is too close to the temperatures expected during local storage and transportation I know.

Two-wheel oriented films can also be made non-shrinkable by heat setting. Ru. Heat setting is the process of constraining the oriented polymer film. while the temperature is above the glass transition temperature of the polyhydroxy acid but below its melting point. This is done by exposing it to. Heat settings known to be effective The duration is from about 1 to 120 seconds, preferably from about 1 to 80 seconds. Main departure Ming's "non-shrinkable" products do not shrink by more than 5% when immersed in boiling water for 1 minute. Defined as an ugly film. Non-shrinkable degradable films can be made by e.g. Used in the production of ready-to-cook food packaging, garbage bags and waste container linings. .

Example The invention is illustrated by the following representative examples of certain preferred embodiments, and in which: All parts, proportions, and percentages are by weight unless otherwise indicated. evening. All units of weight and dimensions other than SI units have been converted to SI units. Ru.

Example 1 Contains more than 85% S- and less than 15% R-asymmetric carbons, about 275.0 Plasticizer with a molecular weight of 0.00 and less than 0.4% as determined by lactide content analysis The polyhydroxy acid composition comprising: 25cm wide vertical die with 2.5mm die gap 28mm Werner-Pfleide with 0.03 and 0.23 mm thickness by twin screw extruder Extrude onto a thin film. These films were prepared at 25 cm diameter, maintained at 20°C. Separate on a chrome-plated cooling roll. Both films are weak and brittle.

A film with a thickness of 0.23 mm was manufactured by T.M.φLong Co., Ltd. (T, M, Lo The initial width and The film is biaxially oriented by stretching it to three times its length. The oriented film is strongly Stiff, optically clear and glossy with good shrink film product yield of 66% It has a reduced value. Place the oriented film under restraint and heat set at 130°C for 1 minute. cut. This film is strong and flexible, making it convenient for non-shrink film products. It has a shrinkage value of 4%.

Example 2 Prior to heat setting, a sample of the biaxially oriented film of Example 1 was prepared with a width of 7.6 cm. m, wrapped around a paper pad measuring 12.7 cm long and 0.64 cm high, adhesive on both sides. Hold it there with tape. Place the wrapped package in a heated air convection oven for 1 Leave at 00°C for 1 minute. The film shrinks uniformly around the pad and is optically clear. Shiny. After storage for 15 months at room temperature, no deterioration of the film was observed; This indicates its usefulness in shrink wrap applications.

On the other hand, it contains more than 85% S- and less than 15% R-asymmetric carbon atoms; A polyhydroxy acid composition with 20% plasticizer determined by cutide content analysis, Extrude according to the method of Example 1 into a film having a thickness of 0.23 mm. several minutes of operation After production, the surface of the cooling roll is coated with a plasticizer, which improves the heat transfer efficiency of the roll. Reduced film thickness and optically poor quality (i.e. approximately 15%) yielding a film surface with cloudy spots ranging in size from up to 40 cm2). However, this indicates that the amount of plasticizer in the initial polymer was too high.

This film was stretched at 46°C using a film stretching machine manufactured by TM Long Co., Ltd. Biaxial orientation is achieved by stretching to three times the original width and length. At room temperature An undesirable soft, cloudy film is produced which has a tendency to shrink.

Example 3 Containing somewhat less than 97% S- and more than 3% R-asymmetric carbon atoms, about Determined by molecular weight and lactide content analysis of 250,000-300,000 A polyhydroxy acid composition having about 5% plasticizer was optically processed by the method of Example 1. extruded into a transparent, 1.5 mm thick film. This film was prepared using the method of Example 1. to produce an optically clear film with a shrinkage value of 71%. Manufacture. On the other hand, somewhat more than 97% S- and less than 3% R-asymmetric carbon Contains elementary atoms, determined by molecular weight and lactide content analysis of approximately 300,000 A polyhydroxy acid composition having about 6% plasticizer was applied to a 1.5 mm thick film. When I push it out, it's cloudy. This film was applied to two wheels by the method described in Example 1. Oriented to produce a film, it becomes brittle after six months of aging at room temperature; This makes the film unsuitable for use in many commercial packaging applications. Let it be.

Summary book The present invention involves melt processing materials to obtain a uniform composition and forming the composition into a film. Polyhydroxy acids and plasticizers, including shaping and orienting films The present invention relates to a method for producing a degradable, shrinkable film made of a degradable and shrinkable film. Also, film The biaxially oriented film is heated above the glass transition temperature of the composition while maintaining the By heat setting at a temperature below its melting point, a non-shrinkable film is manufactured. The films produced in this way can be used in disposable, environmentally friendly packaging. Useful for packaging and other conventional film applications.

international search report

Claims (9)

[Claims] 1. (a) Melt processing a polymer composition containing the following components: (I) at least one hydroxy acid moiety selected from the group consisting of: From about 92 to about 99.9% by weight polyhydroxy acid polymer comprising: (i) (OCR′R′′COOCR′R′′CO)q; (ii) [O(CR′R '')nCO]p; (iii) (OCR'R''CR'R''OCR'R''C O) r; (iv) (OCR′R′′CR′R′′OCR′R′′CR′R′′C and (v) a copolymer of (i)-(iv) with a non-hydroxy acid comonomer. Mar where n is 2, 4 or 5; p, q, r and s are integers; ranges from about 350 to 5,000; R' and R'' are hydrogen; hydrocarbyl containing 1 to 12 carbon atoms; and hydrocarbyl containing 1 to 12 carbon atoms; at least one material selected from the group consisting of substituted hydrocarbyl; and (II) Monomeric hydroxy acid, cyclic dimer of monomeric hydroxy acid, acyclic dimers of monomeric hydroxy acids and monomers with molecular weights up to 450 at least one option selected from the group consisting of oligomers of hydroxy acids of (b) from about 0.10 to about 8% by weight plasticizer; (c) the orientation of the film is adjusted to the glass transition temperature of the polyhydroxy acid; above the melting point of the composition, and the film is biaxial alignment by stretching at least twice the machine and transverse dimensions of the A method for producing a self-supporting film, comprising the steps of: 2. (a) The polymer material is melt-processed while the melt is sufficiently mechanically stirred. , obtain a polymer composition containing the following components: (I) comprising at least one hydroxy acid moiety selected from: up to about 99.9% by weight polyhydroxy acid polymer: (i) (OCR′R′′COOCR′R′′CO)q; (ii) [O(CR′R '')NCO]; (iii) (OCR'R''CR'R''OCR'R''CO ) r; (iv) (OCR′R′′CR′R′′OCR′R′′CR′R′′CO )s; and (v) a copolymer of (i)-(iv) with a non-hydroxy acid comonomer. - where n is 2, 4 or 5; p, q, r and s are integers; ranges from about 350 to 5,000; R' and R'' are hydrogen; hydrocarbyl containing 1 to 12 carbon atoms; or hydrocarbyl containing 1 to 12 carbon atoms; is a substituted hydrocarbyl with sufficient content to form a self-supporting film. and (II) a monomeric hydroxy acid, a monomeric hydroxy Cyclic dimers of acids, acyclic dimers of monomeric hydroxy acids and up to 450 Other oligomers of monomeric hydroxy acids having a molecular weight of about 0. 10 to about 8% by weight plasticizer; (b) forming the composition into a film of uniform thickness from about 0.05 to 2 mm; do; (c) The film thus produced is heated to a temperature higher than the glass transition temperature of the polyhydroxy acid. This is processed in its initial machine and transverse directions at a temperature higher than the melting point of the composition. (d) biaxially oriented by stretching at least twice the dimension of; A biaxially oriented film produced by 1 to 12 to a temperature above the glass transition temperature of the polymer but below the melting point of the polymer. Heat setting by heating for 0 minutes; self-supporting with process Method of producing a sexual film. 3. The polyhydroxy acid polymer has a molecular weight of about 50,000 to about 60,000. 3. The method of claim 1 or 2, having an average molecular weight of. 4. 3. The method of claim 1 or 2, wherein R' consists of hydrogen and R'' consists of a methyl group. 5. The carbon atoms in the polymer chain of the polyhydroxy acid polymer are R- and S −A configuration selected from a group of configurations. 5. The method of claim 4, comprising: 6. 3. The method of claim 2, wherein the duration of heat setting is from about 1 to 80 seconds. 7. (I) at least one hydroxy acid component selected from the group consisting of: from about 92 to about 99.9% by weight polyhydroxy acid polymer containing: (i) (OCR′R′′COOCR′R′′CO)q; (ii) [O(CR′R '')nCO]p; (iii) (OCR'R''CR'R''OCR'R''C O) r; (iv) (OCR′R′′CR′R′′OCR′R′′CR′R′′C and (v) a copolymer of (i)-(iv) with a non-hydroxy acid comonomer. Mar where n is 2, 4 or 5; p, q, r and s are integers; ranges from about 350 to 5,000; R' and R'' are hydrogen; hydrocarbyl containing 1 to 12 carbon atoms; and hydrocarbyl containing 1 to 12 carbon atoms; containing at least one member selected from the group consisting of substituted hydrocarbyl, and (II) Monomeric hydroxy acid, cyclic dimer of monomeric hydroxy acid, acyclic dimers of monomeric hydroxy acids and monomers with molecular weights up to 450 at least one option selected from the group consisting of oligomers of hydroxy acids of Self-supporting polymer containing from about 0.10 to about 8% by weight plasticizer film. 8. 8. The film of claim 7, wherein said film has a shrinkage value of less than 5% at 100°C. Lum. 9. The film has a tensile strength of 80 MPa to 200 MPa and a tensile strength of 30 MPa to 200 MPa. 8. The film of claim 7 having an elongation at break of up to 140%.